Elucidating Unknown Organofluorine in Municipal Wastewater: A Mass Balance Approach including Fluorinated Pharmaceuticals

Previous studies on per- and polyfluoroalkyl substances (PFAS) have indicated large amounts of unidentified organofluorine in municipal wastewater, raising concerns about their environmental impact. Here, a novel multisorbent solid phase extraction method was applied to municipal wastewater samples, followed by liquid chromatography-high-resolution mass spectrometry-based screening and a quantification workflow combining targeted analysis and combustion ion chromatography for fluorine mass balance analysis. Twenty-three highly fluorinated compounds (i.e., perfluoroalkyl acids and precursors) were identified and, apart from trifluoroacetic acid, quantified in the low- to sub-ppt range. In contrast, 30 low-fluorinated substances (i.e., active pharmaceutical ingredients, pesticides, and transformation products, including some previously unreported metabolites) were identified and quantified at concentrations up to 3 orders of magnitude higher. Despite their lower fluorine content (